Devices are known for the distributing of fertilizers associated to seeder machines, usually transported by an agricultural tractor, together able to realise one or more furrows in the terrain, parallel to one another, to deposit a plurality of seeds in each of the furrows and to reclose the furrow and compact the terrain. A seeder machine of known type comprises a metal frame, usually arranged transversally with respect to the advancement direction of the seeder machine and on which a plurality of seeding units is associated. Each seeding unit comprises one or more tanks, or hoppers, which in use contain the seeds to be distributed on the terrain. The tanks are connected to seed distributing devices, for example pneumatically-activated distributor discs, which deposit one or more seeds at regular intervals in each furrow during the advancement of the seeder. The furrows are opened by furrowing organs, and re-closed and compacted by rollers and/or ploughshares connected to the metal frame of the seeder.
Seeders of known type can comprise, optionally, a distributor device of fertilizers able, in use, to distribute additional substances, such as fertilizers or the like in proximity of the furrows for seeding or internally of the furrows specially realised.
The pneumatic distributors of fertilizers of known type comprise a tank internally of which the fertilizer to be distributed is contained, and a conduit internally of which a high-velocity air current flows, generated by a centrifuge ventilator, usually activated by the tractor itself. The fertilizer is inserted by falling from the tank internally of the conduit and transported in suspension internally of a distribution chamber comprising a bell element. The fertilizer product bounces on the surface of the bell and is then directed towards a plurality of openings, fashioned on the bottom of the distribution chamber. The openings are connected to tubes, each comprising, at an end thereof, a distributor nozzle arranged vertically, with the outlet hole facing the terrain.
For example, document U.S. Pat. No. 5,265,547A discloses a selective creation of tramlines where the metered seed normally delivered through the outlet hose of a row planter unit is diverted by a butterfly valve to one or both of row planter units. The diverting hose from the butterfly valve may be connected to Y-shaped connectors having a passage intersecting with the passage that the metered seed for the adjacent row planter units would normally pass for mixing the metered seed.
For example, document U.S. Pat. No. 4,911,090A discloses a seed boot for air seeders including a cast hollow body having a relatively narrow cylindrical upper end intake into which a seed tube may be clamped. Spreaders may be secured to the bottom or discharge end of the boot and can be used to adjust the spread pattern of the seed and an air release slot or vent is provided in the rear wall of the body to reduce air pressure thus reducing the speed at which the seed strikes the ground thereby reducing bounce.
During the course of the numerous experimentations conducted by the present applicant, it has been found that these fertilizer distributing devices include however some drawbacks which make the use of a pneumatic distributor device less than optimal. One of the main drawbacks is given by the nonuniform distribution of fertilizer substance internally of contiguous furrows, and in particular in furrows filled by nozzles connected to the distribution chamber. In some tests carried out by the present applicant, the quantity of fertilizer distributed into the end furrows internally of a group of four contiguous furrows is greater than the quantity of fertilizer distributed into the two central furrows of the group.
In a first aspect of the present invention, the invention aims to obviate the above-mentioned drawback as well as others.